The unidentified include runaways, the homeless and others whose families lost track of them. And now dozens of positive identifications are being made, thanks to improved DNA technology.

Encouraged by the success, the New York City Office of Chief Medical Examiner applied for and received a grant from the National Institute of Justice to continue their work. Investigators are now poring over decades of records.

"We have about 1,200 cases that we are working on that go to the late 1980s," said Dr. Benjamin Figueroa, who is helping to supervise the search effort.

In examining the skeletal remains of unidentified persons, anthropologists are able to extract DNA samples and glean new leads that weren't contained in the original case files. Modern science can now indicate whether remains belonged to a male or female and roughly how old the person was.

"We can go back now and say, for example, it's actually a black female age 17 to 25," said Dr. Bradley Adams. "There's work we can do now with forensic anthropology which couldn't be done back in the time."

Many advances in DNA technology came about from identifying human remains recovered at the site of the World Trade Center attacks after 9/11. Scientists at New York’s new forensic lab are entering DNA samples from exhumed bodies into local and national databases.

But generating the DNA samples is only half the battle, said assistant lab director Mark Desire.

"Equally challenging is to get a DNA profile to compare it to a family," said Desire. "Part of the big push is to make sure reference families' samples get in the system."

Without a DNA sample from relatives, cases often cannot be solved. If some of the people buried are from out of state or overseas, it's especially difficult to make the match.

That appears to be the case with "Baby Hope," the 6-year-old girl whose starved body was found stuffed in a cooler in the woods off the Henry Hudson Parkway in 1991.

"You have information that can make a very straightforward identification, but nobody is looking for that child," said Adams. "Otherwise, there would be a DNA hit. It's hard to believe you'd have a child ... that's still unidentified."

In cases where a DNA match fails, scientists may turn NAMUS, a national website that lists missing people, unidentified bodies and clothing found on bodies.

"The great thing about NAMUS is there is a whole community of volunteers and cybersleuths ... who will analyze what we put on the website," said Figueroa. “There have been a number of times where somebody from the general public has pointed us to a missing person in connection with one of our unidentified."

"We don't pass judgment on who that person was," Figueroa said. "If there is something that can be done, we're going to do it. It's our job to identify that person. Doesn't matter if that case came in today or 20 years ago."

From a legal and financial standpoint, officials say a family can move forward once they have a death certificate in their hands.

In Queens, 83-year-old Gloria Chait has held on to her son Steven's belongings and has renderings of what her son might look like now, decades after he disappeared from his dorm room at Columbia University in 1972.

"I love this kid," said Chait, who still keeps Steven's belongings in his room in their Fresh Meadows home. "No one wants to go 40 years not knowing where your child is."

But she also has a grim hope that the city's new push to identify the "lost souls" of Hart Island may finally give her answers as to what happened to Steven.

"You can't be cynical about this. You have to be realistic and a bit optimistic," said Chait. "You have to understand what kind of suffering goes with a person that disappears. It is immeasurable."